1. Field of the Invention
This invention relates to an electrically-driven camera and more particularly to a camera arranged to perform film winding and rewinding with a motor.
2. Description of the Prior Art
Electrically-driven cameras of the kind performing film winding and rewinding with a motor have hitherto employed various operating methods for shifting a film winding operation by the motor to a film rewinding operation by the motor. These methods of the prior art include:
(1.) A method in which a frame counter is arranged to preset a given number of frames of film. When the film is wound up to an extent corresponding to the given number of frames, film winding is ended. Then, a stroket is disengaged and the film is rewound by operating an operation member.
(2.) A method in which the tension of film developing at the end of winding of the film loaded is detected to end thereby the film winding operation. Then, a sprocket is disengaged and the film is rewound by operating an operation member.
(3.) An automatic rewinding method in which the tension of film developing at the end of the film loaded is detected to end the film winding operation and then to automatically rewind the film by shifting a driving sysyem.
Meanwhile, in the single-lens reflex camera of the kind arranged to be capable of film winding and rewinding with a motor, an operation whereby a mirror which has been retracted at the time of an exposure is brought back to its view finder forming position is arranged to be accomplished in association with film winding. However, when the above-stated winding-to-rewinding shifting methods (2) and (3) are applied to the cameras of that kind, there arises the following inconvenience: Since the film winding operation is arranged to be brought to an end by the film tension which develeps when the whole film loaded has been wound up, the winding phase of the camera at the end of the film varies with the length of the film. Therefore, in case that the film comesto the end thereof in the beginning of a winding process being performed by a camera of the above-stated kind, the winding operation sometimes comes to an end before the mirror is brought back to the view finder forming position. In that event, the camera leaves the mirror in its retracted position. As a result, light is left applied for a long period of timeto the shutter curtain. This not only eventually causes a lekage of light but also, under some extreme condition, might burn the shutter curtain. Further, with the mirror remaining in the retracted position, the view finder is dark and disagreeable to the photographer. Besides, in accordance with the methods (2) and (3), when the camera comes to a stop halfway in the film winding process, the internal mechanism of the camera is left under an unnecessarily loaded condition which affects the internal mechanism even if the camera is not of the above-stated kind having the mirror arranged to be released by a film winding operation.
Another problem of these methods resides in that: When the film is rewound with the winding operation stopped halfway in the winding process, the initial winding extent comes to vary in loading the camera with a new roll of film. This is undesirable because the extent of film feeding by perforation becomes inconstant.
To solve these problems, the present applicant has previously disclosed an invention in U.S. patent application Ser. No. 295,327, filed Aug. 24, 1981, now abandoned. In accordance with the previous invention, the internal mechanism of a camera incorporating a driving motor therein is forcedly shifted to a winding completed state by operating a ewinding operation member, without feeding the film any further, when a winding operation is brought to a stop halfway in a film winding process as the remainder of film becomes small; and a quick return mirror is thus unfailingly moved down to prevent shutter blades or curtains from being damaged and to prevent an accidental exposure to light of the whole roll of film during a film rewinding process. However, the previousinvention has the following shortcoming: In accordance with the method of the invention, the driving force of a film winding motor is arranged to be transmitted to a sprocket by continuously depressing a rewinding operation member in such a way as to cause a switch to allow current supply to the motor. The photographer is thus required to continuously push the rewinding member in carrying out a film rewinding operation when charging is unfinished. However, this is not desirable for the operability of the camera.